681905 has 8 divisors (see below), whose sum is σ = 935232. Its totient is φ = 467568.

The previous prime is 681899. The next prime is 681913. The reversal of 681905 is 509186.

681905 = T₂₉₄ + T₂₉₅ + ... + T₃₀₈.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 681905 - 2⁶ = 681841 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9707 + ... + 9776.

It is an arithmetic number, because the mean of its divisors is an integer number (116904).

2⁶⁸¹⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

681905 is a deficient number, since it is larger than the sum of its proper divisors (253327).

681905 is a wasteful number, since it uses less digits than its factorization.

681905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19495.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 681905 is about 825.7753931912. The cubic root of 681905 is about 88.0186341393.

The spelling of 681905 in words is "six hundred eighty-one thousand, nine hundred five".